The following list is compiled from Marvel when the Intelligencia captured the individuals below for one of their plans of world domination.
Via Marvel Database:
Dr. Reed Richards is considered the most intelligent being on the planet who possesses a mastery of electrical, mechanical and aerospace engineering, electronics, chemistry, physics and human/alien biology. Reed has made breakthroughs in varied fields such as space/time/extra-dimensional travel, biochemistry, robotics, computers, synthetic polymers, communications, mutations, transportation, holography, spectral analysis and much more. He is one of the few people on earth to become an expert on other dimensions and the methods which to travel to and through them. Reed’s patents are so valuable, he is able to easily fund the Fantastic Four and not only has he proven himself a genius on Earth, but he’s been shown to be even more knowledgeable than some of the most highly advanced alien civilizations in the known universe as well.
Dr. Henry Pym is one of the world's foremost biochemists and also possesses considerable expertise in numerous scientific fields such as subatomic physics, robotics, cybernetics, programming, emergency medicine, optics and entomology. His high I.Q. makes him number two of the eight smartest people in the world capable of rivaling others such as Reed Richards and is regarded by the Eternity as the Earth's Scientist Supreme.
Dr. Robert Bruce Banner is a genius in nuclear physics, possessing a mind so brilliant that it cannot be measured by any known intelligence test. According to Banner, he is one of the eight smartest people on the planet at number three. When Banner is the Hulk, his consciousness is buried within the Hulk's and can influence the Green Goliath’s behavior only to a very limited extent. However, recent facts indicate that Banner subconsciously restrains the Hulk's full power.
Victor Von Doom’s most dangerous weapon is his intellect at number four as the eight smartest people. He is one of the top mortal minds on the planet and it’s been debated he’s more intelligent than Reed Richards since Doom cured Ben Grimm from his Thing form when Richards could not. Doom has constructed hundreds of devices to include a working time machine, devices to imbue people with superpowers and many types of robots. His most frequently used robots are his Doombots which look like him, talk like him, and act like him. Individually, Doombots have an advanced AI (artificial intelligence) so that each one believes itself to be the real Doom. As a safety measure, each Doombot has a dampener program that is triggered whenever the real Doom (or another Doombot) is nearby they appear when Doom cannot be present or is unwilling to risk his own life. Doom specializes in physics, robotics, cybernetics, genetics, weapons technology, biochemistry, and time travel. He also has natural talents for leadership, strategy, politics, and manipulation.
Tony Stark is a mechanical engineering prodigy who graduated from the Massachusetts Institute of Technology with honors at the age of seventeen and classed as a super-genius at number five on the top smartest people on Earth. Stark is also known as a futurist and has stated his mind works in an intuitive way where he has even been able to foreshadow a situation similar to Civil War years before it happened. Most recently, Stark’s intelligence has grown to superhuman levels with energy emanating to his brain due to the R.T. node in his chest and it’s later revealed he has been genetically engineered before he was born by Rigellian Recorder 451in order to create the ultimate genius.
T'Challa is a polymath genius and has a photographic memory. His genius is as such that he is one of the eight smartest people on Earth at number six and possesses accomplishments such as a PhD in physics from Oxford University.
7. Amadeus Cho
Amadeus Cho's brain operates like a hyper computer, performing an infinite number of simultaneous calculations which is described as a hyper mind. This allows Cho to identify the variables and quantum possibilities in any situation, and he uses this information to adjust the outcome to whichever is most favorable to him. Though this gift does come in handy when escaping, the strain of his mental calculations leaves him exhausted and famished. His hyper mind also makes him one of the most intelligent people on the planet, ranking him at number seven.
A world-renowned biochemist, Henry McCoy's greatest asset is his keen scientific mind. He possesses a genius-level IQ, with extraordinary expertise in genetics, biochemistry, electronics and other subjects. Beast is also an accomplished keyboard musician and is number eight on the list.
This list is debatable but there you have it. Feel free to disagree and leave your comments/suggestions…